This invention relates to a pipe shearing device, more particularly to a device which accurately shears a pipe into predetermined lengths automatically while the pipe is in constant motion as it is being fed into the device.
There are several types of pipe shearing devices presently known. One of them is provided with a holder means to which a lower blade is fixed while an upper blade is arranged so that it moves up and down by means of a crank mechanism. The holder means itself also is arranged to shift back and forth, parallel to the pipe and its metal pipe carrier, by means of a rack and pinion mechanism.
As both the holder means and the metal pipe carrier which carries a pipe are shifted forwardly at the same speed, the upper blade is so devised as to shift down whereby the pipe carried by the pipe carrier is cut into predetermined pieces in succession in conjunction with the lower blade.
A device of this kind usually requires two power sources, one of which is for the operation of the upper blade and the other for the operation of the rack and pinion mechanism. Such a device not only has power requirements in proportion to the number and capacity of the power sources required, but also the sheared edges of pipes cut by such a device are usually so warped by the shearing force of the upper blade as to form a dimple around the upper portion thereof seen when facing the cut edge of the pipe.
Another conventional device is similarly equipped with a holder means having a square slit along which a sliding member, provided with the upper blade, is arranged to move up and down while the lower blade is positioned at the bottom of the square slit. The up and down movement of the upper blade and the lateral back and forth motion of the holder means is actuated by a motor operated crank mechanism and regulated by a motor controller. However, for accurate and smooth operation, the device may require an additional control mechanism besides the main controller.
Pipe edges cut by this type of device are also so warped by the shearing force as to form a dimple around the upper portion thereof seen when facing the cut edge.
The object of this invention is to provide a solution to the problems of conventional pipe shearing devices.
A further object of this invention is to provide a pipe shearing device which has a pair of counter rotating blades, one of which first cuts a portion of the upper surface of the pipe to form a slit to make it easy for the second blade to cut through the slit to cut the pipe into desired lengths, thus eliminating deformation of the cut edges of the pipe.
Another object of this invention is to provide a compact pipe shearing device to cut pipes held in a moving pipe carrier into precisely predetermined lengths at high speed with a small power source.
A still further object of this invention is to provide a pipe shearing device which is easy to operate by means of a conventional control mechanism.
To this end the present invention provides a structure comprising a holder means connected to a cam follower engaging in a cam groove positioned in a drum cam which is driven by a motor through a gear means whereby the drum cam is rotated to shift laterally back and forth together with the holder means, a pair of rotary blades mounted respectively on a spline shaft supported by a box and arranged to rotate oppositely to each other, and one of the blades being rotated 360.degree. to cut the surface of the pipe carried by the pipe carrier to form a slit, followed by the other blade which rotates 360.degree. in the opposite direction to cut the whole pipe through the slit formed by the preceeding operation to a predetermined length, the pipe cut in this manner being free from deformations of the cut edges produced in conventional pipe cutting devices, a power transmission means which causes the rotary motion of the pair of blades, each blade being rotated oppositely to the other, and a clamp means provided in the holder means to grip the pipe firmly while the pair of counter rotating blades perform the cutting operation through a given clearance between a pair of wall blocks.
The above and other novel features of the invention will more fully appear from following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and not intended as a definition of the limits of the invention.